1. Field of the Invention
The invention relates to a robot apparatus that includes a robot mechanism that has a plurality of joints, and a plurality of actuators that drive joint axes of the robot mechanism, and to a control method for the robot apparatus. More particularly, the invention relates to a robot apparatus capable of flexibly executing desired motions while restraining the amount of electric power consumption, and to a control method for the robot apparatus.
2. Description of the Related Art
In recent years, in conjunction with a robot apparatus that shares a space of activity with humans, there has arisen a situation in which as the electric power consumption of the robot apparatus has been increased, it has become necessary to frequently charge the battery of the robot apparatus. Besides, there also is a technical issue that when a robot apparatus contacts a person, a thing, or the like around the robot apparatus, the robot apparatus needs to flexibly and safely have the contact and simultaneously execute a desired motion. Thus, there is a need for a control of a robot apparatus which is capable of flexibly executing desired motions of the robot apparatus while restraining the electric power consumption of the robot apparatus.
On the other hand, International Patent Application Publication No. WO 00/43167 discloses a robot apparatus that causes the positions of joint axes of a robot to track a posture transition plan that is provided for transition to the next action which has been calculated based on action reference input information. Besides, Japanese Patent No. 3283650 discloses a robot control apparatus that controls various axes of a robot by changing control gains of a servo-control system based on a designated index of the softness related to the coordinate system that the robot has recognized.
However, with regard to the foregoing robot apparatus shown in International Patent Application Publication NO. WO 00/43167, there is a possibility that, for example, a motion reference input from a user may constrain the motions of various joint axes of the robot more than necessary, and therefore the electric power consumption of the robot may increase and the robot may become unable to flexibly contact obstacles around the robot. Similarly, with regard to the foregoing robot control apparatus shown in Japanese Patent No. 3283650, there is a possibility that motions of axes of the robot may be constrained, and therefore the electric power consumption of the robot may increase, or the robot may fail to execute a motion that satisfies a motion reference input when contacting an obstacle around the robot.